Aluminum offset printing plate

ABSTRACT

PROVIDED ON BOTH MAJOR FACES THEREOF WITH PLATING LAYERS ESSENTIALY CONSISTING OF ALUMINUM.   PERCENT MAGNESIUM 0.8-2.5 SILICON 0.2-0.4 MANGANESE 0.8-1.4 COPPER 0.05-0.3 IRON 0.2-0.6 ZINC 0.01-0.2 ALUMINUM BALANCE   AN ALUMINUM PRINTING PLATE FOR USE IN OFFSET ROLLER PLATING COMPRISING A CORE CONSISTING OF AN ALUMINUM BASE ALLOY INCLUDING THE FOLLOWING ALLOYING COMPONENTS:

United States Patent O 3,717,915 ALUMINUM OFFSET PRINTING PLATE Adolf Teuhler, Uedorf, near Bonn, and Paul Eversheim,

Bonn, Germany, assignors to Vereinigte Leichtrnetallwerke GmbH, Bonn, Germany No Drawing. Original application Sept. 24, 1969, Ser. No. 860,805, new Patent No. 3,672,878, dated June 27, 1972. Divided and this application Oct. 26, 1971, Ser. No. 192,621 Claims priority, application Germany, Sept. 27, 1968, P 17 83 066.9; June 9, 1969, P 19 29 146.4 Int. Cl. B32b 15/20; B41n 1/08 provided on both major faces thereof with plating layers essentially consisting of aluminum.

CROSS REFERENCE TO RELATED APPLICATIONS This application is a division of application Ser. No. 860,805, filed Sept. 24, 1969, now Pat. 3,672,878, dated June 27, 1972.

BACKGROUND OF THE INVENTION Materials consisting of aluminum as the base material having a purity of 99% and more have already been used for printing plates in offset printing, particularly for single-color prints. However, these plates were not suitable for so-called roller offset printing. If the aluminum plate or sheet had a tensile strength of about 16 to 18 kp./cm. as required to obtain the necessary stability and rigidity, the danger of tearing of the sheet at the sharp-angled clamping edges is substantial. These edges, however, are necessary for the narrow, tight clamping of the offset plates on the rollers of the printing machine, A tearing of the sheet is particularly disadvantageous if it occurs, not during the initial angling of the edges or during the clamping but, as a result of the centrifugal force during actual operation such as results from the high rotation speed of the printing cylinder.

It is therefore an object of the present invention to provide printing plates for offset roller printing processes which (a) have a high rigidity so as to permit installation in an upstanding position and also to assure form stability during high rotation speeds; (b) are sufliciently flexible to permit the plates, when clamped on the printing cylinder, to conform smoothly and exactly to the surface of the cylinder; and (c) have good angling properties so as to prevent tearing during the acute angle folding or subsequently when subjected to a high tensile stress.

SUMMARY OF THE INVENTION These objects are attained by an offset printing plate which consists of a core comprising an aluminum base alloy containing the following alloying components in the following percentages by reference to the weight of the total composition 3,717,915 Patented Feb. 27, 1973 Percent Magnesium 0.8-2.5 Silicon 02-0-4 Manganese 0.8-1.4 Copper 0.05-03 Iron 0.2-0.6 Zinc 0.01-0.2 Aluminum Balance which core has applied on each of its two major faces an aluminum plating layer.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In addition to the components listed above, the printing plate core in accordance with the invention may also include 0.01 to 0.05% titanium, and 0.001 to 0.005% boron.

A preferred composition for the printing plate core is the following:

Percent Magnesium 1.5 Silicon 0.3 Manganese 1.1 Copper 0.15 Iron 0.4 Zinc 0.1 Aluminum Balance Another preferred composition would have the composition as just described, but would additionally contain 0.03% titanium and 0.003% boron.

The general mechanical properties of the alloys used according to the invention for the printing plate can be seen from the following:

Soft condition:

Yield point: 6 =6-12 kp./rnm. Tensile strength: 6 :17-22 kpt/mm. Elongation: 6 15-30% Intermediate hard condition:

Yield point: 6 =1624 kp./1nm. Tensile strength: 5 :20-28 kp./mm." Elongation: 5 =8-15% These properties will afford a high rigidity, permitting the storage of the plates in upstanding position. It will also assure that the plates are not subject to deformation during the high rotation speeds.

The alloy furthermore has a sufficient flexibility. The plates therefore, when clamped onto the printing cylinder, can be made to conform completely to the cylinder.

These alloys also give the printing plate a good angling property. As a result, the plates will not be subject 0 tearing when they are clamped onto the cylinder and the acute angle edges are being formed. Also, during operation, when the plates are subjected to substantial tensile stress, they will not have a tendency to tear at the clamped edges.

The aluminum base plates formed as described are provided on both major faces thereof with plating layers. These layers may be applied by conventional roller plating processes. The plating layers may for instance consist of pure aluminum of a degree of purity between 99 and 99.9%. Preferably, the plating layers each have a thickness between 2 and 16% relative to the thickness of the entire plate. A particularly preferred plating layer material would be an aluminum plating layer having a purity of about 99.4%.

The plates as noted are provided with plating layers on both major faces thereof which layers are composed of a material which preferably contains the same components as present in the core material but in different percentages. The total plating layers may for instance have a thickness of about 8% relative to the total thickness of the entire plate. The total plate after plating may for instance have a thickness of 0.50 mm.

The following examples will further illustrate the invention.

Example 1 An aluminum offset printing plate was formed by plating in a roller plating process an aluminum core with layers having a combined thickness of about 8% of the total thickness of the plate. The total thickness was 0.50

The compositions of the aluminum alloys employed were as follows (all percentages relative to weight of the total composition):

The properties obtained with this type of plate were as follows:

Yield point: 21.0 kp./mm. Tensile strength: 24 kp./mm. Elongation: 8%

Example 2 The same type of printing plate was prepared as described in Example 1.. However, the compositions of the core material and plating layers were as follows:

Core material: Percent Copper 0.10 Manganese 0.85 Magnesium 2.20 Silicon 0.30 Iron 0.45 Zinc 0.07 Titanium 0.012

Boron 0.003 Aluminum Balance Plating layers:

Copper 0.01 Manganese Traces Magnesium 0.02 Silicon 0.20

Iron 0.41

Zinc 0.08 Aluminum Balance The printing plate of this example had the following properties:

Yield point: 24 lap/mm. Tensile strength: 28 lip/mm. Elongation: 6%

Example 3 An olfset printing plate was formed as described in Example 1 with the following diflierence in the composition of the alloys:

Core material: Percent Copper 0.14 Manganese 1.12 Magnesium 1.6 Silicon 0.25 Iron 0.35 Zinc 0.06 Titanium 0.01 1 Boron 0.002 Aluminum Balance Plating layers:

Copper 0.002 Manganese 0.005 Magnesium 0.004 Silicon 0.20 Iron 0.40 Zinc 0.03 Aluminum Balance The printing plate of this example had the following properties:

Yield point: 13 kp./mm. Tensile strength: 23 kp./mm. Elongation: 18%

The printing plates of all three examples as above described had excellent properties for roller offset printing and were generally considered acceptable by the printers.

We claim:

1. An aluminum printing plate for use in offset roller printing comprising an inner core having the following composition:

and an aluminum base plating layer applied on its two major faces.

2. An aluminum printing plate according to claim 1 wherein said inner core composition additionally includes 0.01 to 0.05% titanium and 0.001 to 0.005% boron.

3. An aluminum printing plate according to claim 1 wherein said inner core has the following composition:

Percent Magnesium 1.5 Silicon 0.3 Manganese 1.1 Copper 0.15 Iron 0.4 Zinc 0.1 Aluminum Balance 4. An aluminum printing plate according to claim 3 wherein said inner core composition additionally includes 0.03% titanium and 0.003% boron.

5. An aluminum printing plate according to claim 1 wherein said aluminum base plating layers consist of aluminum having a purity of 99 to 99.9%. I

6. An aluminum printing plate according to claim 1 wherein said aluminum base plating layers consist of aluminum having a purity of about 99.4%.

7. An aluminum printing plate according to claim 1 wherein said plating layers each have a thickness of 2 to 16% relative to the thickness of the entire plate.

8. An aluminum printing plate according to claim 1 wherein said plating layers each have a thickness of 8% relative to the thickness of the entire plate.

9. An aluminum printing plate according to claim 1 having a total thickness of 0.50 mm.

10. An aluminum printing plate according to claim 1 wherein said core has the following composition:

Percent Copper 0.15 Manganese 1.10 Magnesium 1.12 Silicon 0.30

Iron 0.45 Zinc 0.05 Titanium 0.01 Boron 0.003 Aluminum Balance and said plating layers have the followin composition:

Percent Copper 0.01 Manganese 0.02 Magnesium 0.01 Silicon 0.18 Iron 0.41 Zinc 0.07 Aluminum Balance 11. An aluminum printing plate according to claim 1 wherein said core has the following composition:

Percent Copper 0.10 Manganese 0.85 Magnesium 2.20 Silicon n 0.30

Iron 0.45 Zinc 0.07 Titanium 0.012 Boron 0.003 Aluminum Balance and said plating layers have the following composition:

Percent Copper 0.01 Manganese Traces Magnesium -02 Silicon 0.20 Iron 0.41 Zinc 0.08

Aluminum Balance 6 12. An aluminum printing plate according to claim 1 wherein said core has the following composition:

and said plating layers have the following composition:

Percent Copper 0.002 Manganese 0.005 Magnesium 0004 Silicon 0.20 Iron 0.40

Zinc 0.03 Aluminum Balance References Cited UNITED STATES PATENTS 2,240,955 5/1941 Wood 101-458 X 2,290,016 7/1942 Bonsack 141 2,290,025 7/1942 Bonsack 75-141 2,922,731 1/ 1960 Rutemiller 75-141 X 3,490,955 1/ 197-0 Winter et al 75-141 X FOREIGN PATENTS 1,206,596 9/ 1965 Germany.

CHARLES N. LOVE-LL, Primary Examiner E. L. WEISE, Assistant Examiner U.S. Cl. X.R. 101-459 

